I personally am not a huge fan of the over-the-top themed Kid's Baths. You know, the bathroom that once the child is 16 he looks ridiculous showering in a rubber ducky tiled shower.
I guess if you have all the money and patience in the world to redo your bathroom every five years to keep up with the growing child that's fine.
Most people don't have that kind of money, time or patience though. I suggest designing the bathroom so that it can grow with the child. If you really want to get your rubber duckies in there maybe keep it with the shower curtain instead of the tile. :)
Below are some pictures of Kid's Baths that I think are great.